At present, high-voltage capacitor ignition and transistor coil ignition as well as magnet ignition are known for example for igniting a combustible gas-fuel mixture in the combustion chamber of an externally ignited internal combustion engine. Capacitive plasma ignition also exists as a further development of the known ignition with a discharge across the spark gap of a capacitor connected in parallel (U.S. Pat. No. 5,027,764, U.S. Pat. No. 5,197,448). These plasma ignitions display significant advantages concerning the combustion-technological and economic aspects, compared to the firstly mentioned ignitions. The charged capacitance of the capacitor which is connected in parallel to the gas discharge gap in a direct manner or decoupled by at least one high-voltage diode, is to produce a high current through the gas discharge gap after the breakdown (ionisation). The current values hereby lie at 1 to 1000 amperes. This current in the arc region of the gas discharge produces electrically charged plasma at high temperatures. Locally lean mixtures can be reliably ignited by way of this. The spark combustion duration thereby lies in the region of microseconds.
Disadvantages result due to the thermal electron emission from the hot cathode, which is common in the arc region and which results in a strong erosion of the spark plug electrodes. The gas discharge is greatly constricted with the arc discharge, by which means arc spot formation results on the surface of the cathode. The ignition energy feed is then subjected to large thermal losses, and feed losses moreover arise due to the skin effect with high frequency components, and beam loses in the light arc. A very high quantity of energy must therefore also be consumed. Technically complicated plasma spark plugs are also often necessary. Moreover, a turbulent flame propagation is produced due to this manner of introducing the ignition energy. The course of the combustion has a low flame speed and thus high consumptions and high exhaust gas values of HC and CO, and low torques, above all at a low rotation speed of the internal combustion engine. A knocking combustion can increasingly occur given high compressions.